1. Field of the Invention
The present invention relates to an interior cleaning device for a machine tool, and more particularly, to an interior cleaning device for a machine tool for preventing dripping of coolant.
2. Description of the Related Art
A machine tool has a machining space covered by a cover to prevent scattering of chips and coolant to the periphery. Chips produced by machining by the machine tool may sometimes be accumulated inside this space covered by a cover (hereinafter referred to as “interior”). Then, when the accumulated chips enter a mechanical section of the machine tool, this may lead to breakdown of the mechanical section of the machine tool. Accordingly, to prevent breakdown of the mechanical section of the machine tool caused by entering of chips, the chips accumulated in the interior have to be cleaned.
To clean the interior, cleaning is sometimes performed by using a device (hereinafter referred to as “interior cleaning device”) that sends coolant into the interior by a pump and discharges the chips to the outside together with the coolant.
FIG. 4 is a schematic diagram showing an interior cleaning device. Chips 60 produced by a machining section 1 of a machine tool are accumulated inside a cover 50, and an interior cleaning device 10 is arranged inside the cover 50. This interior cleaning device 10 has a pump, not shown, joined to the interior by a hose 40 or the like, and a pipe 112 is installed in the interior, and holes 116 are opened along the pipe and at the tip end thereof. Coolant C is sent into the hose 40 and the pipe 112 by the pump, not shown, and the coolant C is ejected from the holes 116, and the chips accumulated in the interior are discharged to the outside together with the coolant C. It is also possible to attach nozzles, not shown in the figure, to the holes 116 and to eject the coolant C from the tip ends of the nozzles, instead of ejecting the coolant C directly from the holes 116.
Japanese Patent Laid-Open No. 2008-80464 discloses a liquid curtain generation device for supplying a liquid and generating a curtain film by the flow of the liquid, where the device generates the liquid curtain by ejecting the liquid from a slit formed to a peripheral wall of a tube.
Japanese Patent Laid-Open No. 2003-25180 discloses a technique for prevent scattering of chips produced at the time of machining a workpiece from a curtain liquid coolant film by discharging liquid coolant from a curtain nozzle to the workpiece fixed to a jig.
The techniques disclosed in Japanese Patent Laid-Open No. 2008-80464 and Japanese Patent Laid-Open No. 2003-25180 are for generating a so-called liquid curtain for preventing chips produced by a machine tool from being scattered to the outside, and are different from cleaning of the interior by discharge of chips accumulated inside a cover where a machine tool is installed to the outside. Also, the liquid curtain generation device disclosed in Japanese Patent Laid-Open No. 2008-80464 has a problem described later, because the slit formed to the pipe is formed directly underneath the pipe.
With the interior cleaning device shown in FIG. 4, the coolant C may drip from the holes 116 or the tip ends of the nozzles after the pump is stopped to stop ejection of the coolant C. This is because the coolant C collected inside the pipe 112 drips from the holes 116 or the nozzles due to the gravity after the pump is stopped. To prevent this dripping, the position of opening the holes 116 may be made such that dripping does not occur, but in this case, the direction of ejecting the coolant may be restricted, and chips may not be sufficiently discharged outside. As another method, in the case of attaching a nozzle to a hole, it is possible to attach, in an opposite direction from the gravity, a flexible pipe having a nozzle attached at the tip end and to bend the pipe, but since a flexible pipe of more than necessary length has to be prepared, this increases the cost and also may require a space for installation.